Automatic control system for draw-forming with vibratory energy

ABSTRACT

In a tube-drawing system employing vibratory energy, many difficulties appear as a diameter of said tube, e.g. a charttering mark or a seizure on the surface of said tube, which is based on local friction heat. These phenomena are avoided by an automatic control of which the ratio of amplitude of vibrating energy to tube-drawing speed is adjusted to be in a suitable range of from 1.6 to 11.0.

United States Patent [191 Usui et al.

[11] 31,828,596 Aug. 13, 1974 AUTOMATIC CONTROL SYSTEM FOR DRAW-FORMING WITH VIBRATORY ENERGY [75] lnventors: Genichi Usui, Zushi; lsamu Komine,

Yokohama, both of Japan [73] Assignee: Nippon Kokan Kabushiki Kaisha, Tokyo, Japan [22] Filed: Jan. 17, 1973 [21] Appl. No.: 324,416

[30] Foreign Application Priority Data 3,209,572 10/1965 Boyd et al 72/56 3,209,574 10/1965 Boyd et al 72/56 3,212,313 10/1965 Boyd et a1 72/56 3,295,349 1/1967 Maropis 72/56 3,342,050 9/1967 Fuchs et a1. 72/56 3,657,910 4/1972 lsobe et a]. 72/8 Primary Examiner-Richard J. Herbst Attorney, Agent, or Firm-Moonray Kojima [5 7] ABSTRACT In a tube-drawing system employing vibratory energy, many difficulties appear as a diameter of said tube, e.g. a charttering mark or a seizure on the surface of said tube, which is based on local friction heat. These phenomena are avoided by an automatic control of which the ratio of amplitude of vibrating energy to tube-drawing speed is adjusted to be in a suitable range of from 1.6 to 11.0.

4 Claims, 3 Drawing Figures PATENTED we 1 3 1924 saw 1 or 2 PATENTEDAUB-I 31974 SHEET 2 0F 2 u m @5320 u/ All AUTOMATIC CONTROL SYSTEM FOR DRAW-FORMING WITH VIBRATORY ENERGY BACKGROUND OF THE INVENTION This invention relates to an automatic control system for draw-forming with vibratory energy, and more particularly an improved system capable of draw-forming without generating local friction heat.

Recently, a tube-drawing system employing vibratory energy of ultra-sonic waves has drawn attention as a means of increasing drawing speed and reduction rate and simplifying lubrication. For example, the systems represented by US. Pat. Nos. 3,209,573, 3,209,574, 3,212,312, 3,212,313 and other similar series have been presented and put in practice.

In the usual system, the vibrating energy is impressed by a load switch which acts with tensile force to the plug mandrel or with compressive force to the die. Depending upon the action of the switch, a vibrating sys tem for tube-drawing is driven with a predetermined vibrating wave amplitude. In such case, it is desired to avoid the phenomena of seizure and the like which tend to appear. The phenomena of seizure is produced by locally elevated temperature on the tube with the increase of friction heat, because the drawing speed is near zero in the starting stage of tube-drawing while the vibrating energy is full. When the drawing speed is re quired to be reduced, the operator of the drawing machine is obliged to change the value of the vibrating amplitude. It is well-known that this operation is not always smooth and results in increasing friction heat. The increased friction heat brings about a break of oil film and causes the seizure.

Accordingly, a tube-drawing machine having continuously variable speed has been employed. However, even if the operation of the drawing speed became easy, it still remains a problem that the drawing conditions are not always constant because of nonuniformity of the oil film or change of tool temperature and an actual speed must be decided each time. Consequently, local elevation of the temperature based on the increasing of the friction heat is unavoidable with prior art systems. Such phenomena are based on the difficulties of fixing the most suitable amplitude of vibrating velocity to the tube-drawing speed. When the diameter of the drawing tube is relatively large or when a tube, e.g. stainless, having low thermal conductivity is subjected to drawing, the above difficulties are greatly increased.

SUMMARY OF THE INVENTION This invention has been developed to overcome the above difficulties. A feature of this invention is that the best suited amplitude of vibrating velocity to the drawing speed is automatically established. A set-up value is established which should be selected in the range of from 1.6 to 11.0. The inventors have discovered that the foregoing difficulties are resolved when the ratio of amplitude of vibrating velocity, i.e. angular velocity X amplitude (n), to drawing speed is from 1.6 to 11.0.

An object of thisivention is to provide a system using vibratory energy capable, which automatically adjusts the vibratory amplitude and drawing speed so that the ratio of amplitude of vibrating velocity to drawing speed is within the mostsuitable range.

Another object of this invention is to provide a system using vibratory energy which avoids a break of oil film or a seizure based on the elevating of temperature with increase of friction heat.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 depicts an illustrative embodiment of this invention;

FIG. 2 depicts a block diagram of the control system of the embodiment of FIG. 1; and

FIG. 3 is an explanatory graph on starting behavior of amplitude of vibrating velocity by this invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. I, there is shown an arrangement of each unit of a tube-drawing machine into which this inventive control system is included. A mother tube (1) is drawn through a die (2) and a plug (3) by means of a carriage unit (4), thereby to simultaneously reduce both outside diameter and thickness of the tube (1). Carriage unit (4) acts by a drive motor (12) which is operated through a board (11). A rotating generator, e.g. tachometer (13), is arranged to motor (12) and utilized to measure and control the drawing speed. In a tube-drawing machine, a transfer mechanism may be further added to the above machine. Usually, such transfer mechanism comprises a mandrel (5), a high-frequency power generator (6) an electro-accoustic transducer (7) and a horn for enlarging amplitude, e.g. a coupler (8), of vibratory energy. In such machinism, high-frequency power from the generator (6) is converted into ultra-sonic vibration and enlarged to suitable amplitude by horn (8). Then the enlarged vibratory energy is transferred into mandrel (5) with a form of resonance vibration and vibrates plug (3) connected to the end of. mandrel (5).

In this inventive system, a control (10), used to control vibrating velocity, is further added to the above ultra-sonic vibrating mechanism. The output of tachometer (13) and pickup means (9), which are placed at a suitable location in the above vibrating system and comprise electrostrictive elements, are applied to unit (10). High-frequency generator (6) is controlled by the output of unit (10). The mechanism or components of unit (10) is shown as a block diagram in FIG. 2, and comprises a function generator (14), an amplitude limiter (15), and band-pass filter (16).

The electrical output of pickup means (9), i.e. the present amplitude of vibrating velocity, is applied to amplitude limiter (15), and the output of tachometer (13), i.e. drawing speed, to function generator (14). First, the outputof the tachometer (13), i.e., Ev, corresponding to said drawing speed is converted into f(Ev) by function generator (14). The converting rate, i.e., f(Ev): Ev, is selected from the range of 1.6 to 11.0. Here, said f(Ev) is an output of said function generator (14) in which the suitable range of amplitude of vibrating velocity to various tube drawing speed is preincluded. Such rate is chosen and used to draw a mother tube without any troubles, e.g. a break of oil film, a seizure or the like. Thereafter the output f(Ev) is supplied to amplitude limiter (15). At the same time, the output of the pickup means (9) for the present amplitude of vibrating velocity, i.e. EL is supplied to limiter (15) as mentioned above. In limiter (15), the amplitude E; is readjusted to be equal to f(Ev) through shaping circuit, a comparative circuit and rectifying circuit, which are included into limiter (15) but not 3 4 shown. In such case, Eg corresponds to a change of res- Moreover, in the above-mentioned function generaonance frequency which is based on the changing of tor (14), h Converting of signal Ev, which is an output load or the elevating of temperature of said vibrating r o ng generator of tachometer can be system. Accordingly, the o tp t EC fr li it (15) readily controlled. FIG. 3 shows examples of controlwherein said output f(Ev) from the function generator 5 g of amplitude corrcspqnding to Increase f drawing (14) is readjusted dependingon said EL is kept equal p The Example depleted as curve 15 one of to the regular resonance frequency and as the above propomollal e" Whlch one f the lgeneratlng mentioned converting rate stands, because the changes form of 531d functlon (I Pre'mcludedm 531d funcno" are always adjusted with the above limiter (15). Sucgenerator Oulput thereby Show" as the cessively, output Ec is introduced into band-pass filter to above memloned fig" Examples (2) and (3) r (16). In filter (16) the E0 is filtered to be within a conother examples of i n n we q Stant range and made to be Stable; Consequently, ofthese types ofcontrol can be utilized in this inventive normal oscillation is avoided. Thus, the filtered output Systemis amplified by high-frequency power generator (6), Actual examples based on this inventive system are and impressed to said transducer (7) as the normal and given hereinbelow for illustrative, and not limiting, purstable output E0. Signal E0 is sufficient to assure that poses.

Example 1 Reduction Dimension before drawing Dimension after drawing rate Outside Thickness Length Outside Thickness diameter diameter 23.0 X 1.80 X 6.5 19.0 X 1.50 31.0%

30.0 X 3.00 X 5 25.4 X 2.20 37% Kind of steel: AlSl-304 Lubricant: oxalic acid film metallic soap Vibrating frequency: KH

lmput power: 5 to 8 Kw the ratio of amplitude of vibrating velocity to drawing speed is within the range of 1.6 to 11.0, i.e. the conrequirements: verted rate by said function generator (14) as men- A r d b B mp rm (2: a out 0. tioned above. Because the suitable range of amplitude Ratio of amplitude of vibrating velocity to drawing of vibrating velocity corresponding to the changeable Speed (C): 12.0 range of said drawing speed is preincluded in the function generator (14). I Remarkable seizure was generated on both outside In the above-mentioned control system, an important and inside diameter of said tube. Then, when C was factor is the positive feedback circuit comprising translowered to the range of from 1.6 to 2.0, no seizure apducer (7), pick-up means (9), amplitude limiter (l5), peared. The drawing speed was possible to be increased band-pass filter (l6), and high-frequency power generto the range of 30 to m/min.

' Example 11 Reduction Dimension before drawing Dimension after drawing rate Outside Thickness Length Outside Thickness diameter diameter Drawing speed: llm/min. Kind of steel: ASTM-A-ll Lubricant: resin system liquid Vibrating frequency: 20 KH, lmput power: 5 to 10 Kw ator (6). With such positive feedback circuit, the changes of resonance frequency based on change of pressing the vibratory energy, severe charttering was load or elevation of temperature is easily followed up generated; smooth drawing was scarcely operated.

and regular resonance frequency that is, being bal- When drawn with ratio C of about 3.0, no charttering anced state between said amplitude of vibrating velocwas generated and drawing could be operated without ity and said drawing speed, is kept always stable. any troubles.

Example "1 Kind of steel: AlSl 304 Lubricant: oxalic acid film metallic soap Drawing speed: 34m/min.

Input power: about 10 Kw The above mother tube was drawn with the following When the above mother tube was drawn without im- When the above tube was drawn with ampli tude of 8 p. and ratio C of 17 to 18, remarkable seizure appeared on the surface of the tube.

Being based on the above-mentioned results of examples, the following requirements were confirmed:

l. The above-mentioned ratio C; l;

There are no effects using vibratory energy because of generation of charttering.

2. The C; 1 to 1.5:

An effect using vibratory energy appears, but drawing operations are unstable.

3. The C; 1.6 to 11.0:

Remarkable improvement of drawing speed and reducing rate is exhibited without any troubles.

4. The C; 11:

Friction heat increased, consequently, a break of oil film and seizure tended to generate.

Thus, the ratio of amplitude of vibrating velocity to drawing speed should be readjusted within the range of 1.6 to l 1.0. According to the above-mentioned system, such ratio can be realized automatically and stably without any difficulties.

The foregoing description is intended to illustrate the principles of this invention. Numerous variations and modifications thereof would be apparent to the worker skilled in the art. All such variations and modifications are to be considered to be within the spirit and scope of the invention.

What is claimed is:

1. In a tube drawing method with vibratory energy, an automatic controlling method of tube drawing, characterized in that the actual tube drawing speed is caught as an electrical signal, said signal is converted into another signal corresponding to a ratio of amplitude of vibrating velocity to said tube drawing speed is turned into a predetermined range of from 1.6 to l 1.0 by function generating means, the signal thereby is adjusted in connection with detected actual amplitude of vibrating velocity and then power-amplified, and successively an obtained high frequency power signal is impressed to an electro-acoustic transducer giving said vibrating energy to siad tube therewith.

2. In a tube-drawing system comprising a die, means for drawing said tube through said die at a predetermined speed, and means for applying vibratory energy 6 to said tube during thedrawing, the combination comprising:

first means for monitoring said speed of said drawing;

second means for monitoring the amplitude of vibratory velocity applied to said tube; and third means under the control of said first and said second means for adjusting the ratio of said amplitude of vibratory velocity to said drawing speed to be within the range of from 1.6 to l 1.0.

3, The combination of claim 2, wherein said first means comprises a rotating generator for measuring the speed of drawing of said tube and responsive thereto applying a first signal to said third means; wherein said second means comprises a pickup means attached to said means for applying vibratory energy for measuring the amplitude of vibratory velocity and responsive thereto applying a second signal to said third means; and wherein said third means comprises a function generator for converting said first signal to a function signal representing said ratio of from 1.6 to 11.0, amplitude limiter for comparing said second signal to said function signal and adjusting said second signal to be equal to said function signal and producing a third signal, and a band-pass filter for filtering said third signal before transmittal to control said means for applying vibratory energy.

4. The combination of claim 2, wherein,

said means for applying vibratory energy comprises a high frequency power generator, electro-acoustic transducer for transforming said high frequency power to acoustic vibrations; wherein said second means comprises a pickup means for measuring said acoustic vibrations and converting same to electrical signals; and wherein said third means comprises a function generator for converting said first signal to a function signal representing said ratio, equalizer circuit for adjusting said second signal to be equal to said function signal, and filter means for filtering the signal from said equalizer circuit, and wherein said equalizer, said filter means, said high-power generator, said electroacoustic transducer and said pickup means form a positive feedback path. 

1. In a tube drawing method with vibratory energy, an automatic controlling method of tube drawing, characterized in that the actual tube drawing speed is caught as an electrical signal, said signal is converted into another signal corresponding to a ratio of amplitude of vibrating velocity to said tube drawing speed is turned into a predetermined range of from 1.6 to 11.0 by function generating means, the signal thereby is adjusted in connection with detected actual amplitude of vibrating velocity and then power-amplified, and successively an obtained high frequency power signal is impressed to an electro-acoustic transducer giving said vibrating energy to siad tube therewith.
 2. In a tube-drawing system comprising a die, means for drawing said tube through said die at a predetermined speed, and means for applying vibratory energy to said tube during the drawing, the combination comprising: first means for monitoring said speed of said drawing; second means for monitoring the amplitude of vibratory velocity applied to said tube; and third means under the control of said first and said second means for adjusting the ratio of said amplitude of vibratory velocity to said drawing speed to be within the range of from 1.6 to 11.0.
 3. The combination of claim 2, wherein said first means comprises a rotating generator for measuring the speed of drawing of said tube and responsive thereto applying a first signal to said third means; wherein said second means comprises a pickup means attached to said means for applying vibratory energy for measuring the amplitude of vibratory velocity and responsive thereto applying a second signal to said third means; and wherein said third means comprises a funCtion generator for converting said first signal to a function signal representing said ratio of from 1.6 to 11.0, amplitude limiter for comparing said second signal to said function signal and adjusting said second signal to be equal to said function signal and producing a third signal, and a band-pass filter for filtering said third signal before transmittal to control said means for applying vibratory energy.
 4. The combination of claim 2, wherein, said means for applying vibratory energy comprises a high frequency power generator, electro-acoustic transducer for transforming said high frequency power to acoustic vibrations; wherein said second means comprises a pickup means for measuring said acoustic vibrations and converting same to electrical signals; and wherein said third means comprises a function generator for converting said first signal to a function signal representing said ratio, equalizer circuit for adjusting said second signal to be equal to said function signal, and filter means for filtering the signal from said equalizer circuit, and wherein said equalizer, said filter means, said high-power generator, said electro-acoustic transducer and said pickup means form a positive feedback path. 